We will build on a previously collected prospective cohort of injured older adults accessing 911 emergency medical services (EMS) in 7 counties by matching to pre-/post-injury Medicare data, state trauma registries, state discharge data and end-of-life preferences. We will then evaluate the value of emergency care for injured older patients using long-term outcomes, resource use and costs. Importance: Current EMS triage practices fail to identify many older adults with serious injuries, resulting in transport to non-trauma hospitals (under-triage) and potentially worse outcomes. Under-triage is counter- balanced by over-triage (transport of patients with minor injuries to major trauma centers), which results in unnecessary costs, disruptions in care and no measureable benefit. However, there is little research to describe and understand these issues, particularly in older adults. This project will rigorously address EMS triage practices unique to older adults, including the role of comorbidities, medication use, end-of-life preferences, functional survival, resource use and costs. We will also validate new triage guidelines to better identify seriously injured older adult and compare to current triage practices. This project will fill key scientific gaps and inform the next revision of national EMS triage guidelines. Objectives: The proposal has 3 specific aims: Specific Aim 1. Describe the current emergency care system for injured older adults, including out-of-hospital triage processes, reasons for selecting hospitals, short- and long-term outcomes, resource use, and costs. Specific Aim 2. Refine and validate a previously derived out-of-hospital risk stratification tool to better identify seriously injured older adults that could be incorporatd into national triage guidelines. Specific Aim 3. Estimate the overall programmatic impact (benefits, harms and costs) of triage guidelines from Aim 2, compared to current triage guidelines. Study Design: This will be a secondary analysis of a 7-county, population-based, prospective EMS cohort, matched to pre- and post-injury Medicare data, two state trauma registries, two state discharge databases and the Oregon Physician Orders for Life-Sustaining Treatment (POLST) registry. Setting: The setting includes 7 counties in Oregon and Washington (urban, suburban and rural regions), 44 EMS agencies and 44 acute care hospitals (4 major trauma centers and 40 non-tertiary hospitals). Participants: The study will include 17,909 injured adults = 65 years transported by EMS to 44 hospitals between 1/1/2011 - 12/31/2011, representing the denominator of older adults to whom the field triage guidelines are applied. Patients with serious injuries (Injury Severity Score = 16) will define high-risk patients. Outcome measures: Outcomes will include 1-year functional survival, resource use (repeat EMS transports, repeat ED visits and re-admissions), and health care costs up to 1-year post-injury.